Scientists from Würzburg and Lübeck in Germany are attempting to improve the quality control of 3D bioprinted tissue implants. Their “PhotonControl” system uses both Optical Coherence Tomography (OCT) and Raman spectroscopy (Raman) to test fabricated tissue.

With its ability to repair damaged areas of the human body in a safe and cost-effective manner, 3D bioprinted tissue is on the rise. But since printed tissue is a relatively new concept, it’s important that scientists use thorough quality control measures in order to maintain patient safety.

Unfortunately, that is often easier said than done: quality control can be difficult, due to the complex printing processes used to fabricate the tissue and the sometimes long period of maturation after printing is complete.

A new research project being carried out across two German institutes—the University Hospital of Würzburg and the University of Lübeck—proposes a new system for quality control of bioprinted tissue. It aims to assess the fabricated tissue both during the 3D printing process and during tissue maturation.

“Biofabrication is a research field still in its infancy,” commented Professor Jürgen Groll, Chair for Functional Materials of Medicine and Dentistry at the University Hospital of Würzburg, who has highlighted the need to create an effective method of quality control for these new medical creations.

Groll’s system, called “PhotonControl,” uses two distinct methods of testing. These are Optical Coherence Tomography (OCT), an imaging technique for capturing 3D images of biological tissue, and Raman spectroscopy (Raman), a laser technique that is generally used to observe vibrations and rotations.

Together, these processes can be used to ensure the proper quality of 3D bioprinted tissue for use in human patients. Perfecting the process, however, has proved difficult.

“Quality control during the printing process is a major challenge,” Groll said.

Part of the reason for this difficulty is the researchers’ decision to avoid using chemical markers, which make quality control easier but which can damage the tissue being observed.

“We cannot, for example, use any chemical dyes,” Groll explained, “as they can affect the tissue maturation of the printed constructs.”

The researchers say that the most important part of the process is capturing the relevant relevant chemical, biochemical, and morphological information about the tissue, rather than its speed or level of detail. For this reason, they have opted for non-invasive techniques.

Both OCT and Raman were chosen because they are non-invasive, and do not require chemical markers. The two processes also complement each other: OCT allows structural imaging in real time, and can quantitatively measure mechanical properties; Raman provides molecular information on the chemical and biochemical characterization of the 3D printed structures.

PhotonControl will be developed further over the next two years by Groll and Dr. Gereon Hüttmann from the Institute for Biomedical Optics at the University of Lübeck.

Around 240,000 euros ($283,000) has been provided for the project by Germany's Federal Ministry of Education and Research (BMBF).